Methods of delivering metal ions in reaction media for co-action with moieties to achieve specific effects are well established.
For instance, a number of inorganic substances have antimicrobial activity because of the toxicity to microorganisms of the ions into which they dissociate. It has been established in antimicrobial activities that salts of heavy metals are rapidly precipitated by extraneous organic or other material and, therefore, while such salts may have an initial cell kill at an initial effective concentration, the effective concentration is rather quickly reduced by combination of the metal with such extraneous matter, thereby depleting the amount of toxic metal available for biocidal activity. Therefore, while inorganic salts offer in certain instances the property of aqueous solubility and, therefore, dissociation for availability as toxic metal agents, they may be rendered rather quickly ineffective such that prolonged or controlled destruction or inhibition of bacterial action is unavailable. On the other hand, metal salts or complexes of organic moieties such as organic acids or the like possess a degree of dissociation which is normally not as great in comparison to, for example, highly soluble inorganic salts. Therefore, whereas the metal organic salts or metal complexes may have a greater stability or kinetic inertness with respect to extraneous organic matter present in the environment of living cells, there is also generally a loss of toxic effect by reason of their higher stability. Representative of prior art patents directed to the use of metal salts or metal chelates of inorganic or organic compounds as microbiocidal agents are: U.S. Pat. Nos. 871,392; 991,261; 1,679,919; 1,785,472; 2,208,253; 2,269,891; 2,456,727; 2,494,941; 2,878,155; 2,900,303; 2,091,393; 2,938,828; 3,076,834; 3,099,521; 3,206,398; 3,240,701; 3,262,846; 3,266,913; 3,681,492 and 3,782,471.
In other instances, various prior art approaches have been taken toward the improvement of metalworking compositions and in an effort to overcome or minimize direct and indirect disadvantages involved in the use of such metalworking fluids. Representative of prior art patents in this area are U.S. Pat. Nos. 2,688,146; 3,240,701, 3,244,630 and 3,365,397. Such patents and the efforts of others in substance have been directed to overcoming the factors contributing to emulsion deterioration and breakdown by the addition of metal compounds and complexes.
In substance, in such prior art processes there appear to have been two extremes made available. On the one hand, known metal compounds have a high degree of dissociation such that metal ions are quickly and copiously made available by virtue of rapid dissociation with formation of ionized species. These species react so as to saturate all available reacting moieties; and thereby are rendered inactivated in a very narrow time frame, thus rendering them relatively ineffective as biocidal agents, or metalworking stabilizers and the like, over prolonged periods of time. Other known metal compounds are relatively stable and provide minimal amounts of ionized species with minimal effects.